Surfing Waves

Aloha Riders !
So guys here is the situation, Im a relatively skinny guys 160lbs (muscles not fat) 6"1~6"2 tall... been surfing regularly for the last 15months, 1 to 3 times per week, it is very addicting, anyways i started on a 8" softTech foam board, then changed after a few weeks to a 7" foamboard as well. lately i have been thinking to go down to a short board, I tried a 6"2 Fish, 21' in width double fins, and I surfed great on it. but it wasn't mine its my friends now I was thinking about getting something shorter like a 6" short board that is pretty wide maybe same width! is tht a good idea or will be frustrated ?
the question is , should I get a fish 6"2 ? or a shortboard 6" ?

If you surfed great on a board of that size then go ahead. Just make sure it's similar dimensions to the fish, and not some 6'x18x2 toothpick.

Few weeks on a sponge 7 footer, tried a 6'2" Fish and now want to buy a 6'0 "true" shortboard ? Well I'm having fun on my 250cc. cruiser bike. "Tried" my friend's 500cc. sports bike and could do it. What do you think if I get a 750cc. or maybe even a 1000cc. You think that's wise ?
Going shorter shouldn't be your goal. Surfing the wave should be. If you can "surf" the wave on a 6'0" shortboard, than go for it. But if it's too hard to paddle, too hard to catch, too hard to make the bottom turn, THEN that's not surfing ( and not fun )
If you are not maximizing what you can do on your current board ( bottom turns, cutbacks, pull outs, all going frontside and backside ) , I would say it's not a good idea to get a shortboard until you master the Funboard and Fish first.

I'll ask wkk's question in a different way: why do you want a 6ft shortboard?

Your question is a bit like someone saying 'I want to get a BMW M3, should i get one?'. Well, the answer is 'it depends on why you want it and what you are sacrificing to get it'. Sure if you have the money and dont need to transport tools and 3 kids around; no if you are just swayed by the badge but actually a station wagon is going to best meet your requirements

There is nothing magical about a 6ft board or a 6ft2 fish. There is no reason to get one unless you have a reason and you understand and accept the 'sacrifices' (paddling, less margin for error, fewer waves, less stable etc).

If you think you were surfing great on the 6ft2 fish and that is your reason (you 'surf great' on shorter boards) and you dont think you were sacrificing much, then get a shorter board. The difference between a wide 'shortboard' and a 'fish' is probably pretty minimal - its probably just called a fish due to a swallowtail and maybe a slightly lower rocker or rounder nose, but I suspect its wasnt a 'fish' in the traditional sense. In other words, I wouldnt get too worked up about the differences.